Genetic variation in the ribosomal internal transcribed spacers of Aphanomyces astaci Schikora from Finland

Ribosomal Internal Transcribed Spacers (ITS) have been the most popular source of DNA data for phylogenetics and PCR detection. In this study, we investigated intraspecific and intragenomic DNA polymorphism of ribosomal ITS regions of the crayfish plague causing pathogen Aphanomyces astaci Schikora, groups Pacifastacus I and Astacus. A total of 36 ITS regions of A. astaci were sequenced from 18 new isolates and 31 polymorphic sites were analysed and compared. We also compared data produced in this study to previously published A. astaci sequences in the NCBI GenBank. We observed a 3.2% polymorphism level in 23 cloned sequences. Even though polymorphism was observed in ITS regions, Finnish A. astaci isolates could not be grouped (into either PsI or As) based on these differences.